The present invention relates to a disk array apparatus and disk array apparatus controlling method.
In various fields, primary importance is attached to environmental issues and a cost reduction in recent years. There is a trend among disk array apparatuses to deal with these problems by reducing power consumption. US2003/0193732A1 discloses a method of controlling access from an information processing apparatus to each hard disk drive group (RAID group) of a disk array apparatus and setting all hard disk drives which make up the RAID group to a power saving mode when there is no access for a certain period of time.
Furthermore, the disk array apparatus is required to prevent trouble with the individual hard disk drives and extend the life of the entire disk array apparatus. US6057974A discloses a method of carrying out operation of setting hard disk drives to a power saving mode (stopping spinning of magnetic disks) one by one at predetermined time intervals and thereby preventing trouble with the hard disk drives without drastically reducing the access performance.
The method according to US2003/0193732A1 sets all hard disk drives to a power saving mode for each RAID group. For this reason, when an information processing apparatus issues a request for access to a logical volume of the above described RAID group, it is necessary to cancel the power saving mode first and then respond to the access request, which drastically reduces the access performance. Thus, there is a demand for a reduction of power consumption at hard disk drives without drastically reducing the access performance.
Furthermore, a disk array apparatus combining a plurality of hard disk drives with different interface standards is used in recent years. The interface standard is, for example, a fiber channel and serial ATA. Compared to a fiber channel hard disk drive, a serial ATA hard disk drive has lower reliability and shorter life. However, the serial ATA hard disk drive is less expensive than the fiber channel hard disk drive, and so the serial ATA hard disk drive is used for tasks other than key tasks, and the serial ATA hard disk drive and fiber channel hard disk drive are often used discriminately according to their applications.
For example, suppose a disk array apparatus consists of a fiber channel hard disk drive and a serial ATA hard disk drive. In this case, since the serial ATA hard disk drive has shorter life, the life of the entire disk array apparatus is shortened by being influenced by the life of the serial ATA hard disk drive. For this reason, when the disk array apparatus consists of hard disk drives according to a plurality of interface standards, there is a demand for extending the life of the hard disk drives. Using the method disclosed in US6057974A can set hard disk drives one by one to a power saving mode, thereby prevent trouble of the hard disk drives and extend the life of the hard disk drives, but the method in US6057974A discloses no considerations about the case where a disk array apparatus consists of hard disk drives according to a plurality of interface standards.
The present invention has been implemented in view of the above described problems and it is an object of the present invention to provide a disk array apparatus and disk array apparatus controlling method.